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Ashok Mannolu Arunachalam, How toArraysJSES6
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How to remove array duplicates in JavaScript

The Set collection

Since ES6, Set collection has been introduced which is really good and makes our life simple. Set is a collection which will not keep duplicates. It can also take any iterable objects as constructor arguments. In our case, it is an array with duplicated values.

js
const duplicates = [1, 2, 3, 3, 2, 1]
const unique = [...new Set(duplicates)]
console.log(unique) // [ 1, 2, 3 ]

Array.filter function

It is better to know more options, in case of not-so-friendly environment. For instance, Set collection is supported by all the major browsers but few old-schools. Yes, I am looking at you IE! O_o

js
const duplicates = [1, 2, 3, 3, 2, 1];
const unique = duplicates.filter(
(item, index) => duplicates.indexOf(item) === index
);
console.log(unique); // [ 1, 2, 3 ]

Please prefer the Set option just for the simple of it!

We can do the same .indexOf trick using .map, .foreach as well. But, .filter is more readable among those! ^_^